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Your code compiles just fine for me. What version of PGF are you using (I'm using PGF2.10)?
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Loop SpaceJan 28 '12 at 19:41

judging from the usage of the snakes library he is using an older version. Compiles fine here as well by the way.
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Roelof SpijkerJan 28 '12 at 19:54

Hm, funny thing is that now I've updated to pgf 2.10: went to sourceforge and unpacked the entire thing into ~/texmf. But running pdflatex again gives the same error, although \pgfversion says 2.10
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IlonpilaajaJan 29 '12 at 15:54

SOLVED: updating the pgf installation (as above) plus removing the space between \coordinate[ns]_(x4) did the trick. Now (I know there is no topic discussion in comments) what's wrong with the space? I have a Finnish keyboard, and sometimes when compiling C-programs gcc also complains about "stray \302 in line x", so these two issues can be connected...
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IlonpilaajaJan 29 '12 at 16:18